Author: tabimori

What is Toro salmon?

You probably already know this, but “toro tuna” is not the name of a type of fish. “Toro” is the name of a fatty part of the tuna. The fat content and attributes of the belly side of the tuna are completely different from that of the dorsal side. Toro is the name of the part near the head, mostly on the belly side.

In the same way, there is no fish called “toro salmon”. Just like tuna, “toro” refers to the fatty part on the belly side of the salmon. It is also called “harasu” in Japanese. This is how the word is used at some scrupulous sushi restaurants. This description of “toro salmon” is correct.

Most salmon used at conveyor belt sushi restaurants is either trout salmon or Atlantic salmon. The reason this salmon can be served at the cheap price of US $1 or $2 per plate (2 pieces of sushi) is that these particular fish are all farmed and are available in bulk quantities from overseas. This salmon is mainly imported to Japan from Norway, Chile, Scotland and Canada.

Actually, the popular “toro salmon” topping is made from these imported items and the fat content is three times that of wild salmon. Feeding farmed salmon plenty of solid compounded feed that is high in protein and high in fat, turns the entire body to toro.

Salmon, which are born in freshwater and migrate downstream to the sea are called “sea-run fish” and they may be farmed in either seawater or freshwater. Trout salmon is “former” rainbow trout that was raised in a fish cage in the sea. In the wild, the sea-run rainbow trout grows up to 1 m in length, its body turns silver and the meat takes on a red color. The wild version of these are called “steelhead” and fetch a high market price, so they are not used in conveyor belt sushi restaurants.

Just like other aquaculture, salmon farming faces some difficult issues. It may surprise you that salmon is actually a white fish, originally. In the wild, the salmon meat gets a red color from feeding on crustaceans such as crab and shrimp that contain the red pigment astaxanthin. However, in the fish cages where the salmon are surrounded by nets, the food chain is also restricted. The compound feed would be plenty if the goal was only to raise bigger fish, but that results in a grey color or light yellow meat that doesn’t even resemble the salmon pink (orange?) that everyone wants and they don’t sell.

Therefore, when making the solid compounded feed, artificial coloring is mixed in. One of the colorings is called canthaxanthin. This is a synthetic chemical derived from petroleum. There is a color chart with 10 different, detailed levels of red coloring and buyers can even indicate which color they would like and the farmers can achieve it. It’s kind of like an industrial product that is being manufactured. Japanese people prefer a dark red color for salmon in the same way they do for tuna, so the coloring for Japan’s market is adapted to that.

When light is shone on wild salmon, the red coloring looks faded, but the light makes farmed salmon that have been fed coloring, look brighter. Artificial coloring is a necessity in farmed salmon and this is true for the trout salmon and Atlantic salmon that are used as the ingredients for toro salmon as well. All of the farmed salmon in circulation have been colored in this way, so much so that it wouldn’t be surprising if the insides of their stomachs were stained red. The flamingos at zoos also get their beautiful pink feathers from these chemicals.

Trout salmon is rainbow trout that has been farmed in the sea. On the other hand, rainbow trout farmed in freshwater is called Donaldson trout. Of all the large rainbow trout gathered at each location, those with small heads and fat bodies were selected and bred over many years to create this type. The objective of choosing a small head is to make more meat. They are characterized by their fast growth and while normal, farmed rainbow trout grow to about 30 to 40 cm, Donaldson trout grow up to nearly 1 m. The name is taken from the American who developed this variant.

The Donaldson trout is farmed throughout Japan and is used as toro salmon and aburi salmon at conveyor belt sushi restaurants. Since they are supplied directly to the processor (of the salmon) from the farmer without going through the market, they may be sold cheaper than the import price. Just like the imported salmon, this farmed salmon is also fed artificial coloring. There are also already new variants improved from the Donaldson trout being bred. Trout made from breeding Donaldson trout females and steelhead males are called Donaldson steelhead, for instance. They grow even faster.

Ample use of the latest biotechnology has been made in salmon farming and some of these technologies include creating young fish without functioning reproductive organs, “triploids” which means increasing the size of the fish up to triple and “all female populations” where males are converted into females. The triploid fish grow large in correlation to the lack of energy exertion. The objective of all-female populations is to get more masuko (ovaries). Masuko is used for the ikura (salmon roe) at conveyor belt sushi, and since the fish that the roe is harvested from have an inferior flavor, they are used for aburi salmon. Now, there are even triploid, all-female farm populations. No wonder the restaurants can serve a plate (2 pieces) of salmon sushi for US $1.

The simple phrase, “toro salmon” contains so much meaning.

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Related contents:

What is Beni toro?

What is Biwa trout?

What is Brown trout?

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Revision date: February 16, 2023

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Why is salmon so delicious?

Few foods manage to captivate the senses as completely as salmon. From its vivid orange color to its buttery texture and gentle sweetness, salmon is beloved around the world—in sushi bars, on breakfast tables, and at fine dining restaurants. But what makes this fish so irresistibly delicious?

When you put food in your mouth, the components that are dissolved by your saliva are called extract components. Extract components include mainly free amino acid and inosinic acid as well as organic-based components such as adenosine triphosphate-related substances, creatine and trimethylamine oxide. Extract components are important components that make up the flavor of foods.

When we looked up the extract component composition of the muscle of chum salmon, sockeye salmon, coho salmon and king salmon, which are all types of salmon, the component composition of chum salmon, sockeye salmon, coho salmon and king salmon are all similar.

The taste of fish is much lighter in comparison to the muscle meat of shrimp, crab and squid types of seafood. By combining extract components, shrimp, crab and squid flavors can be reproduced, but the relationship between the flavor extract components and fat in fish meat plays an important role in taste. The fat of fish gives it a rich flavor, illustrated by the fact that compared to the back meat of fish, the taste of the belly meat, which is abundant in fat to protect the organs, has a richer flavor.

The difference between the muscle of salmon and tuna is that salmon tends to have a lower inosinic acid content. Although not unique to salmon, the delicious taste of fish meat is related to the amount of inosinic acid and the amount of fat. Umami is mainly made up of inosinic acid is strongly related to fat and in case of inosinic acid content is high, it doesn’t feel “fatty” even with high-fat content. Instead, the fat makes it more pleasant and delicious.

On the other hand, when the inosinic acid content is low, a high-fat content doesn’t really translate into a pleasant taste. In the case of farmed fish, where high importance is attached to the weight of the fish when it is shipped, even if the fat content is high, if the inosinic acid level is low, then the fatty aspect does not translate into deliciousness, which is likely what leads to the opinion that the flavor of farmed fish is inferior to wild fish.

In the case of salmon variations, the inosinic acid content is low compared to tuna variations, and generally, the optimal amount of fat for delicious salmon is 4 to 6%. With tuna, the general idea is, the more fat, the more delicious, but this is not true for the taste of salmon.

Fat on animals that live above ground hardens when refrigerated. This creates an unpleasant waxy texture when eaten. However, as fish live in the frigid ocean waters, their fat doesn’t harden, even when stored at about -18℃.

In addition to flavor and fat composition, the appearance of salmon also plays a role in its deliciousness. The vivid orange to reddish color of salmon flesh comes from astaxanthin, a natural carotenoid pigment that the fish obtain from their diet. This bright coloration is not only visually appealing but also stimulates the appetite. The striking color signals freshness and richness, enhancing the perception of taste even before the first bite.

Another key factor is the texture. Salmon muscle fibers are relatively soft, and its fat has a low melting point. This combination creates a smooth, almost buttery mouthfeel that melts on the tongue in a way few other fish can match. The sensation of delicate flesh blending with rich but gentle fat is one of the reasons salmon feels especially satisfying.

From a nutritional perspective, salmon is also considered a “deliciously healthy” food. It is rich in high-quality protein and packed with omega-3 fatty acids such as DHA and EPA, which are known to support brain function, reduce inflammation, and promote cardiovascular health. The knowledge that salmon is not only tasty but also beneficial to the body enhances the sense of satisfaction when eating it. This connection between flavor and health further explains why salmon is so universally appreciated.

The most appealing aspect of salmon is thought to be that it goes well with shari (vinegared rice). The meat is soft and the fat has a low melting point, so it blends easily with shari and emits a sweetness when you bite. This is a sensation you won’t find with much other fish.

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Revision date: August 19, 2025

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Nutritional and Functional components of Unagi

According to Japan’s Fisheries Agency, based on their consumer’s behavior survey, Unagi (Eel) always ranks number one under, “Fish Japanese people want to eat.” The highest consumption of unagi throughout the year is in the hot summer months. Since long ago, Japanese people have been captivated by unagi as a food with high nutritional value and have loved it as a measure against heat fatigue. Here We would like to explain the nutritional and functional characteristics of unagi.

Unagi distributed domestically in Japan used to include European eel, but currently, it is mostly Japanese eel. In Japan, the overwhelmingly most popular way to eat unagi is “kabayaki”. Kabayaki mainly refers to a grilled fish cuisine in which unagi or anago (conger eel) is prepared by slicing open along the spine and removing the bones and guts, then skewering it, and grilling without any seasoning, steaming it (Some area, unagi is just grilled longer without steaming. This results in the unagi a little crispier and chewier) after that, and finally dipping it in a sauce made from a mixture of soy sauce, mirin, sugar, sake, etc.

The interesting thing is that the level of free amino acids, deeply related to flavor, is relatively low compared to other seafood. The fatty acid composition and volume don’t change even from heating and it also doesn’t significantly alter the free amino acids, so the flavor of unagi itself is light compared to the flavor of other kinds of seafood. Therefore, this is a big factor in Japanese people thinking of kabayaki sauce when they imagine the unagi flavor.

When the general components of unagi are compared with other fish (flounder, horse mackerel, sardines and bonito) and when they are compared with livestock (cattle, swine, chickens), unagi has the highest caloric content of 255 kcal per 100 g fortis edible parts and it also has the highest fat content (19.3 g per 100 g). Furthermore, it has significantly less fiber than beef or pork, so it is easier to digest. Collagen is present in all vertebrates, but the content is particularly high for eel. Of the minerals contained in the muscles, there is 130 mg calcium for every 100 g, which is much higher than other foods, even higher than milk. There are also abundant amounts of vitamins A, E and B in the meat. 50 g of kabayaki contains more than the recommended daily intake of vitamin A for an adult male and prevents oxidation of the fat, along with vitamin E. Especially high amounts of vitamin B1 are found in all seafood, and vitamin B2 and pantothenic acid contents are also relatively high. Meanwhile, the unagi is also known for having extremely high levels of vitamin A and folic acid in the internal organs.

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Revision date: February 9, 2021

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Learn the basics of pairing sake with sushi!

First, let’s roughly categorize sake. The two main indicators that determine category are aroma and intensity. Is the aroma fragrant or mild? Is the taste mellow or sharp? This creates 4 categories, fruity (aromatic with a mellow flavor), light (mild aroma with a mellow flavor), umakuchi (mild aroma with a strong flavor) and matured (aromatic with a strong flavor).

Next, we will introduce the characteristics of each of the four categories, and the basic sushi toppings that pair well with each one.

When a fruity sake is poured into a glass, and when you take a drink, there is a sweet aroma that is almost fruity. The taste is juicy and elegant. We recommend pairing it at the beginning of a meal. However, the aroma may be overpowered by seafood, so it’s quite difficult to pair it with sushi. However, don’t be too concerned with the general theories, and instead, feel free to discover your own original pairings. We think fruity sake can be paired with robust-flavored fatty toppings such as fatty tuna and Splendid alfonsino, or rich flavored toppings such as sea urchin and conger eel.

e.g. Dassai Migaki Niwarisanbu, Dewazakura Ichiro Junmai Daiginjo, Born Kantsubaki

Light-flavored sake goes down easy and has a clean aftertaste. It is a refreshing taste. The aroma is very mild and it doesn’t linger. This type of sake goes with a wide variety of foods, and it is the best sake to drink while eating a meal of sushi. It goes especially well with delicate flavors like cuttlefish and octopus and it goes with toppings that have enjoyable aromas such as shellfish.

e.g. Hitakami Yasuke, Hakkaisan Tokubetsu Honjozo, KUBOTA HYAKUJYU Tokubetsu Honjozo, Koshi no Kanbai Ginjo Bessen

Umakuchi sake has a subtle aroma, the innate sweetness of the rice, and a strong umami flavor. It is also characterized by the wide range of temperatures at which it can be served, from room temperature to the very hot “tobikiri-kan” (55℃ or higher). The aftertaste lingers a bit, and you won’t tire of it even when drinking for a long time as part of your meal. This type of sake goes well with fatty Horse mackeral (Aji) or Japanese sardine (Iwashi). It also goes well with toppings known for umami flavors such as Japanese amberjack (Buri), oyster and salmon roe.

e.g. Shinkame Junmaishu, Tengumai Yamahai Junmai

The moment matured sake is poured into a glass, it gives off a condensed aroma reminiscent of dried fruits. As the amino acids and sugars have changed over several years, it has an interwoven complex flavor and aroma. The aftertaste lingers and it is characterized by its smooth texture on the tongue. This sort of sake goes well with potent and fermented crucian sushi.

e.g. Daruma Masamune Koshu, Hyakurakumon Junmai Koshu

Overall, the most important thing is that neither the sushi nor sake overpowers the other, and that the flavors and aromas harmonize in your mouth, without fighting each other. For example, sushi with a clear, rich flavor and a high umami content should be paired with a full-bodied sake, and subtle delicate-tasting sushi should be combined with a smooth and refreshing sake. That’s the basics.

Main Types of Sake

Generally Japanese sake is made from rice and water, but it can be divided into two major categories depending on whether extra alcohol is added or not. Sake without added alcohol is called Junmaishu (純米酒). When alcohol is added, it’s called Honzojoshu (本醸造酒) or Futsushu (normal sake).

Ginjoshu (吟醸酒) and Daiginjoshu (大吟醸酒) sakes are extremely rare as they were originally made as entrants in competitive exhibitions. A lot of careful work goes into the production from the selection of the rice used, high-precision milling, making of yeast and yeast mash, all the way to the final preparations.  If the milling percentage is 60% or less then it is ginjoshu. At 50% or less, it is Daiginjoshu and you can find variations of both Honjozoshu (sake without added saccharides and 120 liters or less seed alcohol per ton) and Junmaishu (sake without added alcohol or sugar). The Honjozoshu variations are just called Ginjo or Daiginjo sake, but the Junmaishu versions are called Junmai Ginjo and Junmai Daiginjo sakes.

Alcohol is added to Honjozoshu before the pressing process in order to bring out the fragrance and attain a pleasant balance. The additive amount is always the same and remains within 10% of the weight of the raw rice used. The milling is also kept to 70% or lower. While it is more fragrant than Junmaishu, the flavor is clean and refreshing, making it pleasant to drink.

Futsushu (ordinary sake) is sake that uses rice with a milling percentage of 70% or more, with distilled alcohol that uses 10% or more white rice, or non-distilled alcohol added as a raw ingredient.

Sake Glossary

On the label of sake, various characteristics are printed – how to brew, press, heat, stock and so on. It is sure that you can be more delighted to taste sake after knowing them.

Sake-brewing rice (酒米)：It means rice cultivars suitable for sake making.

Rice polishing ratio (精米歩合) ：It is the weight percentage of white rice to brown rice.

Sake meter value (日本酒度)：It is used as a general indicator of dry- and sweetness in sake. However, sweet and dry are sensory perceptions, where SMV is simply a reflection of specific gravity, so the two do not always appear to correlate. The sugar glucose is sweet, but, the more other sugars influence the SMV, the less sweetness will be apparent. Further, the sense of sweet or dry is affected by the level of acidity. The higher the acidity, the drier the sake will taste. Sake with low acidity tends to taste sweeter.

The average Sake meter value range is from 0 -＋5. Sake sweeter than the zero mark (that is to say in the minus range) is considered ama-kuchi ; that which reads more than +5 may be said to be kara-kuchi. According to the Tax Agency’s market survey of sake products in 2012, the average values for various types of sake were: futsu-shu +3.7; ginjo-shu +4.3; junmai-shu +4.

Acidity (酸度)：Those organic compounds which register as acidic are called organic acids, and these comprise almost all the acids found in seishu. 73% of sake acids are produced by yeast during the main fermentation, with about 17% coming from shubo, and the remaining 10% from steamed rice and koji.

Organic acids are important components of sake taste, giving acidity (sourness) and umami, with volatile acids also contributing to the aroma. In order of volume, there is most succinic acid, followed by malic acid, lactic acid, citric acid and acetic acid. In moromi, succinic acid is produced in the greatest amounts, followed by malic acid, then lactic acid. At the yeast starter stage, most lactic acid is produced, followed by acetic acid and succinic acid.

According to Tax Office statistics for 2012, the respective levels for futsu-shu, ginjo-shu and junmai-shu were 1.18, 1.32 and 1.50.

Amino acid content (アミノ酸度)：The amino acids in seishu exist in the form of salts, and (together with lower peptides) displaying slight sweetness, umami, acidity and bitterness, are constituents of sake flavor. Where amino acid levels are too high, the sake is hard to drink with high levels of zatsu-mi off-flavor. When amino acid levels are low, the sake will be thinner and kirei (“clean”). Primary examples of amino acids include glutamic acid, glycine, alanine, valine, arginine and so on. Monosodium glutamate is sometimes used as an auxiliary material.

The average range of amino acids in sake is from 1.0 – 2.0. Light examples with a value of less than 1.0 can be said to be tanrei (light) sake, low in amino acids. Sake with high levels of amino acids at more than 2.0 will be full-flavored sake, often described with the adjective (noujun; tanrei and noujun may be considered opposites).

According to Tax Office statistics for 2012, the respective amino-acid levels for “regular” sake (futsu-shu), ginjo-shu and junmai-shu were 1.25, 1.30, and 1.54.

Kimotozukuri (生酛造り)：

The first process of brewing sake is a pure culture of yeast to sake seed mash. Kimotozukuri is a traditional method of using lactic acid bacteria in this step. Sake made by this method is characteristic of the strong taste.

Yamahai-shikomi (山廃仕込み)：

In the kimotozukuri method, the process of mixing rice and koji into a puree is cake Ymaorosi. In the meiji period, it turned out that it can also be done by a function of enzyme and yamaorosi process was abolished (haishi). This new method was called Yamahai.

Muroka-Namagenshu (無濾過生原酒)：

As these sakes are not filtered and heated, you can enjoy their rich flavor. They have high alcohol content because not added water.

Nigorizake (にごり酒)：

This sake is cloudy sake just made by filtering with a coarse cloth. One which is not pasteurized is called Kassei-nigorizake.

Namachozo-shu (生貯蔵酒)：

Namachozo-shu is stored raw and pasteurized once when bottling.

Namazume-shu (生詰酒)：

Namazume-shu is stored after pasteurized once and then bottled raw.

Nama-shu (生酒)：

Nama-shu is stored raw and then bottled raw.

Hiire (火入れ)：

Hiire is stored after pasteurized and pasteurized when bottling.

Fukuro-sibori (袋搾り)：

The press method for premium sake like Daiginjo. To put the fermentation mash into a sake bag and drip with no pressure.

Hiyaoroshi (冷おろし)：

New sake completed in early spring becomes aged well and the wildness of its taste is removed after stored during the summer. It is shipment in autumn.

Shiboritate (しぼりたて)：

Sake shipped immediately after pressing in a sake brewery. It has a fresh taste.

Related contents:

PAIRING SAKE101

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Revision date: February 4, 2021

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What is the difference between denbu and oboro?


Oboro and Denbu are traditional Japanese ingredients often used in sushi and other dishes, known for their delicate texture and sweet flavor. While they may look similar and share many ingredients, understanding their subtle differences and uses can enrich your appreciation of Japanese cuisine.

Oboro and Denbu look the same, and the ingredients are also pretty much the same. In other words, there are no clear differences between them, but what it is called differs depending on the restaurant’s policy and the locality. There are various theories for this, but there is no clear line distinguishing oboro and denbu.

Denbu (田麩) is mainly boiled white fish that is then loosened and made into fibers, then seasoned with sugar, mirin, salt, etc., then roasted until the moisture is gone. The most commonly used fish for denbu are Tara (Cod) and Tai (Red seabream), which have a mild flavor and light color suitable for this preparation. Some are colored with red food coloring (called sakura denbu) while others are left as the brown color similar to tsukudani. The appearance is as if only the fibers of the original ingredients remain. This is why it was written with the kanji “田夫” (the literal meaning of kanji: rice patty+husband). The word “田夫” means “someone from the countryside” or “rough-cut” and refers to the way the fish is turned into a coarse form by pulling the meat apart. It is also used as a coloring for chirashizushi, futomaki (large sushi rolls), bento boxes, etc. Because of its bright color and sweet flavor, denbu is often used to add visual and taste appeal to children’s meals and festive dishes in Japan.

On the other hand, Oboro (朧) is made by using a grinding bowl to break down the meat of shiba shrimp or white fish, then seasoning with sugar, mirin and salt before removing the moisture over low heat. Oboro is used for bara-chirashi, futomaki (large sushi rolls), etc., and is also sometimes used between the topping and shari (vinegared rice) in nigiri sushi. This practice enhances the subtle flavor of the fish, serving as a base layer of umami, while helping the sushi topping blend more harmoniously with the vinegared rice. Oboro acts as a kind of “glue” between the neta (sushi topping) and the shari (vinegared rice), and it also adds a soft visual accent to the overall presentation. This gentle sweetness and the shrimp aroma are essential for Edomae-style sushi. Making oboro is laborious work, so there are fewer and fewer Edomae-style sushi restaurants that make their own oboro.

Although the distinction between Oboro and Denbu can be subtle and varies by region and restaurant, both play an important role in enhancing the flavor, texture, and appearance of Japanese dishes. Next time you enjoy sushi or chirashizushi, paying attention to these ingredients can deepen your culinary experience.

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Revision date: August 5, 2025

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What is Fugu poison?

Why do people risk their lives to eat Fugu, a fish known to be deadly?

Fugu, or blowfish, is a celebrated delicacy in Japanese cuisine, but it comes with a deadly risk. Despite its exquisite taste and refined culinary presentation, Fugu contains one of the most powerful natural toxins known to humans. Understanding what makes this fish so dangerous—and how it’s safely prepared—sheds light on one of the most fascinating aspects of Japanese food culture.

In most cases, Fugu (blowfish) poison is found in non-meat parts of the fish such as the liver, ovaries, stomach, intestine, skin and eyes. There are Fugu that do not contain poison in these parts, but most of the Fugu in the waters near Japan are poisonous. A mistake in preparations that allows the meat to touch the poison of the liver or ovaries results in immediate death. Therefore, the general rule is to only eat Fugu at restaurants with an expert licensed in Fugu preparation. Cases of poisoning by Fugu are nearly always a result of an amateur trying to prepare the fish.

The toxin in Fugu is a chemical substance called tetrodotoxin and even heat from boiling or frying can’t detoxicate it. Even Torafugu (Japanese pufferfish) that we find so delicious (we eat the meat, skin and testes) has poison in the liver, ovaries and intestines. The toxicity is said to be at least 1,000 times that of potassium cyanide. They say 10 people would die from the organs of a single Torafugu. In the case of Fugu poisoning, the first poisoning symptoms occur between 20 minutes and three hours after eating the Fugu. It starts with numbness in the lips, the tip of the tongue and fingertips. This is followed by headache, stomachache and severe vomiting. The victim will stagger when trying to walk. Soon they will experience sensory paralysis, speech disturbance and difficulty breathing, accompanied by a decrease in blood pressure. After that, the entire body becomes paralyzed and the victim can no longer move even a finger. Finally, they will fade out of consciousness and eventually both breathing and heartbeat cease, resulting in death. If the consumer doesn’t notice they are experiencing poisoning symptoms, they will surely die.

The strength of the toxin of the fugu also varies depending on the season. Even on an individual basis, some fish have toxins while others don’t. It’s not possible to determine this based on appearance, so it’s better to never eat the organs and eyes, which have a high probability of containing poison.

Fugu has already been successfully farmed and is on the market. No toxins have been found in this farmed Fugu. If farmed Fugu has no toxins, it’s only natural to question what factors generate toxins in wild Fugu and apparently it‘s a cumulative effect of toxins from the food chain. Fugu’s main sources of nutrition are starfish and shellfish. Starfish and shellfish accumulate poison in the body by eating zooplankton with vibrio attached to them. This vibrio creates poisons. Then, Fugu accumulates toxins in the body by eating starfish and shellfish that have toxins accumulated in their bodies. Therefore, farmed Fugu are raised on man-made feed that doesn’t contain Fugu toxins, and since they don’t ingest Fugu toxins and there is no bioconcentration, so the Fugu does not contain poison.

Enjoying Fugu safely requires more than bravery—it requires expertise.
While the thought of eating a potentially lethal fish may seem reckless, the strict regulations and skilled craftsmanship behind Fugu preparation make it one of the safest delicacies when handled properly. As farmed Fugu becomes more common and toxin-free, the dangers may be diminishing—but the mystique surrounding this unique fish remains as strong as ever.

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Revision date: August 7, 2025

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What is Shusseuo?

During the Edo period, samurai would change their names at Genpuku (coming-of-age ceremony and career stages. Following this tradition, fish that are called by names as they grow older/larger are called “shusseuo (出世魚)”, are considered lucky and are used in cooking to celebrate milestones in life.

Shusseuo doesn’t just change in name, they also change in taste. The bigger the body, the more fat. However, young fish also have their own delicious, refreshing taste unique to their age. For example, using the young fish for deep-frying and fatty fish as sashimi is an interesting way to put it.

In addition to fish commonly referred to as “syusseuo,” there are other fish whose names change as they grow. According to “A Study of Japanese Fish Names,” there are 82 species of fish whose names change as they grow. Bluefin tuna (Maguro) and Greater amberjack (Kanpachi) are representative examples. Maguro changes from “komaji” to “meji” to “maguro” to “oomaguro.” Kanpachi changes from “mojaco” to “shiwoko” to ‘akahana’ to “kanpachi.”Fish such as konoshiro, sawara, unagi, sake, and koi are not considered “syusseuo.” It is not the case that all fish whose names change as they grow are classified as “syusseuo.” Rather, these are fish whose taste improves as they grow, undergo minimal changes over time, and were highly valued in eras when preservation and transportation technologies were not yet developed.

Incidentally, opinions are divided on whether to call Maguro “Shusseuo.” Maguro is also called “Meji” or “Chubou” when it is small, and its name changes as it grows. Fishermen distinguish between different stages of Maguro before it becomes an adult fish, but when it is sold in stores, even if it is slightly small, it seems that people tend to trust the name ‘Maguro’ and do not treat it as a fish that has “made it.”

A good representative fish of shusseuo is the yellowtail (Buri). Its name changes as it grows and there are various forms of their names depending on the region. In the Kanto region, it changes from Wakashi (15-20cm) to Inada (30-40cm) to Warasa (60cm) and then to Buri (80cm or greater). It is said to be most delicious at 40 cm or longer and even if the body is plump, inada often has little fat.

Even if the name is the same, depending on the region, it may be referring to a different size. For example, inada is a fish up to 40 cm in Kanto but in Tohoku and Tokai, it refers to small fish of 15-20 cm. Further, although it is not related to its growth, those caught in Tohoku during summer are called “ao”. In Toyama, they are called “gan” and “gando”.

Finally, the changing names of fish demonstrate the breadth of culture. We should cherish this local diversity present in the names of our fish that capture the abundant food culture and importance of the seasons.

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Revision date: August 8, 2025

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What is Artificial caviar?

Caviar refers to salted sturgeon ovaries but in many European countries, caviar is also used as a generic term for fish roe. In its home of Russia, roe is generally called “ikura” and caviar specifically refers to black fish roe.

Caviar is one of the world’s three major delicacies and can command different prices depending on the type of sturgeon (egg size). It is ranked in the order: Beluga, Oscietra and Sevruga, all of which come from the Caspian Sea. Beluga from the Caspian Sea is designated as an endangered species and international trade is prohibited by the Washington Convention. Its population is very small and it does not lay eggs until 20 years into its lifespan, so the resource has yet to recover. This has brought the market price of Beluga up to around USD $400 for just 50 g.

What is the substitute for caviar?

Lumpfish roe is sold as a substitute for caviar. The size of each egg is about 2 mm in diameter and it is colored with squid ink. This gives it a taste and appearance similar to caviar. The market price is an astonishing USD $5 per 50 g.

The main ingredients of Lumpfish caviar are as follows:

  • 　Lumpfish roe
  • 　Salt
  • 　Sugar
  • 　Thickening agent
  • 　Sodium benzoate
  • 　Coloring

What is artificial caviar?

Artificial caviar is significantly cheaper than genuine caviar. It’s low in fats, lower in calories and healthier than the real thing. It is already a big hit in the U.S. The size of the eggs is a little larger than authentic caviar and the skin is thicker but most people would tell you the texture and taste is much the same. There has also been a decrease in sturgeon, and there is no sign that its price will fall in the future. The challenge is meeting the global demand through a combination of farmed caviar which has become a more stable supply in recent years, with the ever-dwindling wild caviar. The market price is reasonable at around USD $10 for 50 g.

There is a way to tell the difference between real caviar and fake caviar.

an image of caviar on the cracker First, place the caviar on a cracker. Fake caviar (made of Lumpfish roe) has added color, and this color will bleed onto the cracker within about 30 minutes. However, the color will not transfer to the cracker from real caviar.

The main raw ingredients of artificial caviar are as follows:

  • 　Sea urchin extract
  • 　Oyster extract
  • 　Gelatin
  • 　Dextrin
  • 　D-sorbitol
  • 　Trehalose
  • 　Gelling agent
  • 　Seasoning
  • 　Coloring

Finally, seafood with a high price, unfortunately, results in substitutes, counterfeits, and artificial products. Masquerading a fake as the real thing can result in a large profit. I will tell you that it is difficult to trick a middleman who serves professional sushi chefs or restaurants. Therefore anyone in Japan who uses seafood like this, does it knowingly, which makes the crime even worse.

Related contents:

What is Salmon caviar?

What is Red caviar?

The secret story of how Ikura became a sushi topping!

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Revision date: February 22, 2022

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What is Izumidai?

When you see “tai” on the menu at a conveyor belt sushi restaurant, it’s very likely that is not “madai” (Red sea bream). It’s a competitive industry where these conveyor belt restaurants have no problem using a variety of imitation or replacement fish if it means they can cut costs. In any case, the purpose for using different types of fish without even considering farmed cheap madai, is to further reduce costs.

First on the list is Nile tilapia. This fish was introduced from Egypt to rivers throughout the world as food in 1962. While it was farmed in large quantities in Japan, especially in Kagoshima, from the 1990s, production rapidly declined with the stagnant prices of farmed madai. However, they are extremely fertile and proliferate naturally, and started living in the thermal regions and the rivers where warm wastewater flow throughout Japan.

The commonly used names for this is “izumidai” or “chikadai”. While izumidai (Nile tilapia) is a freshwater fish, it was likely named after “tai” (sea bream) because of the similarities in appearance. In Taiwan, it is considered to be so similar in appearance and taste, that it is called “Taiwanese sea bream”. It is a popular fish for consumption on a global scale with high production and distribution volume.

However, even though has “sea bream” in the name, it is not actually related to the sea bream at all.

As an aside, at least 90% of the tilapia found in the U.S. is imported. Most of those imports come from China. It’s often said that they are raised on a large volume of antibiotics and pesticides, and they are kept fresh using high amounts of chemicals. It’s best to avoid eating it if possible. The tagline they give it is “Sushi grade tilapia is a high quality, firm fish with a mild, clean taste perfect for sashimi and sushi applications” You’ll be hard-pressed to even find kaiten sushi restaurants using this in Japan. In addition, it would never be used at restaurants that describe themselves as Edomae Sushi.

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Revision date: January 4, 2021

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What is Engawa?

Engawa has both a unique, crunchy texture and delightful fat distribution and is said to be the most delicious part of hirame.

But what exactly is engawa?

a photo of Engawa nigiri
Engawa is not the name of a fish, but a generic term for a specific part of a fish.

Engawa is the generally used name for the meat muscle that moves the soft ray of the dorsal and ventral fins of flatfish (such as Hirame and Makogarei). Most people in Japan think of the hirame version when they hear the word ‘engawa’.

To go into a more advanced level of detail, there are three types of muscles that move the dorsal and ventral fins in fish: the erector spinae, the depressor and the scalene muscles. These muscles are well-developed in fish that move their dorsal and ventral fins often, like flatfish and flounder. Actually, not all three of these types are always consumed. If we look at the way hirame and makogarei are cut for preparation, the slanted muscle is taken to be used for engawa while the erector spinae and depressor are left, affixed to the fin ray, etc. In other words, to be exact, engawa is the slanted muscle of the dorsal and ventral fins.

The unique, crunchy texture comes from the high content of collagen, which is a scleroprotein. “Kakushi boucho” is used to make the crunch pleasant and is one of the skills a sushi chef must perfect. The delicious flavor is related to the high amount of fat compared to body meat. There is also a sense of elegant sweetness. Only four pieces of engawa can be taken from a single flatfish, so it makes sense that foodies love it.

The name “engawa” comes from its resemblance to the unique veranda structure of Japanese-style homes. This veranda is called “engawa” in Japanese.

Incidentally, substitutions have become common at kaiten sushi (conveyor belt sushi) restaurants, and the topping is especially popular among women lately. So the question is, how is it possible to eat this valuable topping that is only rarely available at expensive sushi restaurants, so cheaply at kaiten sushi? Actually, Greenland halibut engawa and Kamchatka flounder engawa are used as substitutes to hirame engawa. The proof of this is in a menu that lists only “engawa” and not “hirame engawa”.

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Revision date: December 3, 2020

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What is the difference between Fish farming tuna and Fish fattening tuna?

While high-quality tuna toro used to be unattainable for normal people, it’s now become a much more affordable item. This is thanks to fish fattening (畜養) practices of the southern bluefin tuna, which is equivalent in quality to the Pacific bluefin tuna. The fattening method of catching young southern bluefin tuna in roll nets or something similar, and then keeping them in fish preserves until they grow big enough was developed in the 1990s in Australia.

There have been changes in the Pacific bluefin tuna as well. In the late 1990s, the southern bluefin tuna fish fattening method started to be used in the seas throughout the world, and this led to the fattening of the Pacific bluefin tuna, which became all the rage. Most of these are exported to Japan, and account for about half of the consumption of southern bluefin tuna and Pacific bluefin tuna in Japan.

As a bonus, tuna that has been fattened in this way has such a high volume of fat that it is said to be “all toro”, and it’s taken the Japan high-grade toro market by storm. Also, both southern bluefin tuna and Pacific bluefin tuna are served at kaiten-zushi (conveyor belt sushi) restaurants.

The fattening of Pacific bluefin tuna started on the east coast of Canada in the mid-seventies. In the summer, large volumes of Pacific bluefin tuna are caught in the fixed shore nets on the Atlantic seaboard, and since they have already spawned, they have slimmed down and aren’t worth much commercially. These fish are fed and fattened, and a new route to Japan has been developed, giving the fish new commercial value.

Both fish fattening and fish farming (養殖) mean to hold fish in fish preserves, but the purpose differs between the two. The purpose of fish fattening is an adjustment for fishing while the purpose of fish farming is to grow fish to a certain size. Therefore, in fish fattening, they are not fed food to promote growth, but they are in fish farming. However, even in fish fattening, if the period of time they are held for shipping adjustment stretches out too long, they are fed in order to prevent a decrease in meat quality and cannibalism. This can blur the line between fish fattening and fish farming quite a bit.

The Pacific bluefin tuna fish fattening started in Canada is similarly vague. In that case, the purpose was fattening, so it may be fair to call it fish farming. However, shipping adjustment was also one of the major objectives. What about the fish fattening of southern bluefin tuna and Pacific bluefin tuna in Australia and the Mediterranean Sea? These are in place clearly for the purpose of growing small fish, so we can call them fish farming.

In the Mediterranean, where resources are already declining, methods are used to catch natural tuna alive. The only mobile fishing gear that can catch tuna alive is purse seine nets.

The period when tuna are transported to the fattening farms is generally from May or June to July or September, but this varies depending on the country. They are then transferred to cages, where they are fattened for a relatively short period to meet Japanese market standards. The fattening period is usually six to seven months, because demand in the Japanese market peaks at the end of the year. In Croatia, the size of tuna transferred to cages is small, so the fattening period can be as long as 20 months.

Mediterranean coastal countries involved in tuna fattening include Algeria, Croatia, Cyprus, Greece, Libya, Malta, Spain, Tunisia, and Turkey. French tuna purse seine fishing fleets are the largest suppliers of live tuna to fattening farms in Mediterranean coastal countries.

The Kindai University Aquaculture Research Institute has succeeded in a complete farming process of taking eggs from spawning Pacific bluefin tuna, incubating them and raising adult fish. Research for a complete farming process began around 1970, so it has taken 30 years for success. These fully farmed tuna are also raised in fish preserves and fed small fish like sardines as well as artificial feed for fattening, resulting in all-toro tuna. However, even though the Kindai University tuna have been featured by the media, you never see them in the supermarket. Why is that? Even though the university has succeeded in a mass-production method, the absolute quantity is extremely low even though raising the fish takes a lot of time and effort, so the price is extremely high.

Whether they are fattened, farmed, or fished in the wild, consumers always welcome delicious, high-quality toro at a reasonable price.

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Revision date: May 28, 2025

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What is a firm difference between sushi and western fish cuisine?

In Japan, they say, “Japanese cooking means taking away and Western cooking means adding.” This concept is well-known among Japanese chefs, but it may be difficult for western chefs to understand. This is verified in the way the white Japanese sea bass, the representative fish of summer, is prepared. This is all connected to clearly explaining the irrefutable differences between sushi and western fish cuisine, which also involves differences in cultivated history and culture.

In the case of Sushi, a representative of Japanese cuisine, the decisive point is to prepare the fish in a way that removes the fishy odor characteristic of Japanese sea bass. At the same time, the finished piece should be a simple dish that can be enjoyed with only a minimal amount of nikiri soy sauce and wasabi, so as not to override the natural refreshing flavor and umami of the fish. It should let the customer imagine sea bass swimming in the summer sea. And yet, the deep flavor required for the dish is successfully brought out using only a balanced combination of vinegar rice, the topping, wasabi and soy sauce. The method is really just to take out the excessive elements of the dish.

Meanwhile, the method for making sea bass dishes in French cuisine, representative of western cooking, includes seasoning the fish with salt and pepper and saute in butter, then adding rich, creamy sauce as well as other things like herbs, caviar, black truffles, etc., creating a dish that allows enjoyment of multilayered flavor. This sort of dish beautifully makes up for the flavors that the light, white fish lacks and portrays a flavor with depth through the finished plate over the individual flavor of the sea bass. In this cuisine, it can be said that the cooking method is more important than the raw ingredients. It can be thought of as cuisine that adds many ingredients.

Comparing the two, it’s clear that the approaches are completely opposite. Another difference is how the flavors are treated. Flavors perceived through aroma can be described as “aromatic flavor”.

If this fragrant flavor were not important in sushi, then there would be no debate on whether to use wild or farmed fish. For example, sea bream is available both in the wild and as farmed fish. There is not much difference in amino acid composition and umami content between the two. So how is it that farmed sea bream and wild sea bream end up tasting so different? The reason is undoubtedly the aroma. The subtle aromatic compounds, volatile substances carried in the fish’s fat, are what define the essential flavor of the sea bream. Wild fish, having fed on a natural diet and lived in varied ocean environments, develop a more complex and refined aromatic profile. In contrast, farmed fish, raised on controlled feed in uniform conditions, lack this nuance. This means that much of the pleasure of eating sushi comes from recognizing and savoring this delicate aroma.

On the other hand, in Western fish cuisine, the culture is to combine many different aromas, as if composing a perfume, probably because people want complex flavor. In addition, in French and similar cuisines, care to serve dishes at a temperature that is warm, but not hot, in order to bring out the natural flavor of the ingredients. While cooking the dishes, the temperature is strictly controlled so that the components of the ingredients don’t change from the heat, in order to maintain the taste and aroma. This method does not neglect fragrance by any means. In sushi, the fish itself is the centerpiece, with preparation methods designed to remove distractions from its inherent character. In Western cuisine, the plate as a whole is the centerpiece, where the fish is one component in a carefully constructed harmony of flavors.

In either method, the one essential element is this “aroma”. The only true difference is how that is expressed.

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Revision date: August 11, 2025

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How can frozen tuna be thawed to still taste good?

In order to maintain the quality of tuna, when it is caught in the sea, the ikejime technique is used first, then rapid freezing is used as a matter of course. This means that the quality of the thawing technique is also important. Poor thawing conditions mean that the drip outflow volume will be too high, shrinking the meat and worsening the texture. Here I will explain a thawing method that doesn’t cause drip, uneven thawing, or loss of color.

What exactly is drip anyway?

I’m sure you’ve seen it before in any type of thawing frozen meat, but there is a red liquid that comes out of the tuna when thawing. This is called ‘drip’. This liquid includes the tuna’s umami, and when the fish loses a lot, it naturally detracts from the flavor.

First of all, we will explain the worst thawing methods. Never thaw naturally at room temperature or in the microwave. These are common methods at home, but they are out of the question.

Next we will explain the general method of thawing.

  1. Mix 30 g of salt with 1000 cc of warm water at 40℃ to create a saltwater mixture.
  2. Place the frozen block of tuna in this 40℃ saltwater, submerge for one to two minutes and then drain the water.
  3. Wash any remaining salt off the surface of the block of fish with fresh water and remove moisture from the surface with paper towels.
  4. Wrap the fish in clean paper towels, wrap with plastic over that and leave it in the refrigerator for about a day to thaw naturally.
  5. Cut from the block directly before consuming.

Now for the thawing method used by professionals, such as sushi chefs.

The first three steps are the same as the general thawing method above.

  1. Place block in an air-tight plastic bag. Push out as much air as possible before sealing the bag.
  2. Prepare ice water in a bowl or container and submerge the plastic bag in the water for one hour. Normally the bag will float, so it must be weighed down with something.
  3. Remove the thawed tuna from the plastic bag and remove moisture with paper towels.
  4. Wrap the fish in clean paper towels, wrap with plastic over that and leave it in the refrigerator for about a day to mature.

After thawing, the meat of the tuna may have shrunk. This is called ‘chijire’. The reason for this is, after the tuna is caught, it is frozen before rigor mortis begins, so the rigor mortis process starts once the fish is thawed. Therefore, this is proof of freshness. The meat of tuna for which ‘chijire’ has begun is tough and isn’t yet matured. However, amateurs can’t tell if ‘chijire’ is happening or not. That’s why it’s better to let the fish mature in the refrigerator for half a day to one day. Please use these explanations for your own reference.

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Revision date: October 2, 2020

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The secret story of how Ikura became a sushi topping!

Between the time Edomae sushi was born (1810-1830) and around 1930, the toppings used in nigiri-sushi were strictly limited to slices of seafood. There were no so-called delicacy toppings (such as salmon roe and sea urchin, etc.).

However, in 1934, a restaurant in Ginza called Kyubey started a revolution. This restaurant is still synonymous with high-end sushi, but at that time many political and business people went there as well. Then, one night… Apparently, one of the regular customers was tired of eating ordinary sushi and said to the chef, Hisaji Imada, “I want to eat some sushi that is more unusual. Ikura (Salmon roe) sounds like it would make good sushi,” as a joke. Imada, who took these words seriously, thought to himself, “But the roe would fall off if put directly on the shari (vinegar rice),” and racked his brain that night for a solution. Finally, he had an idea and said, “I know, I could just surround shari with seaweed and put salmon roe in it.” This is how the Ikura Gunkanmaki was born.

Next, when that customer came in again and Imada nervously served him his new Ikura sushi concept, it was received much better than expected. Gaining confidence from this reaction, Chef Imada put it on his regular menu. The story goes that rumors of the delicious taste spread and other sushi restaurants started to copy it. Then, the term “ikura gunkan-maki”(salmon roe battleship roll) was coined.

Nowadays, everything is used as battleship roll toppings from sea urchin to shirauo to negi-toro to mayonnaise and canned tuna-fish. It goes without saying that it all started with salmon roe.

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Revision date: September 25, 2020

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What’s the trick to distinguishing which conveyor belt sushi restaurants are better?!

There is only one trick to distinguishing between conveyor belt sushi restaurants (kaiten-zushi), and that is to try eating the tuna as your first dish.

Why is that, you ask?

The most commonly used ingredient at kaiten-zushi is tuna. At kaiten-zushi, the tuna is imported and frozen nearly 100% of the time. The most famous is the Southern blue-fin tun, but you’ll also find Boston bluefin tuna, Canadian tuna farmed in fish preserves, inland sea tuna from Turkey and Spain, New Zealand offshore tuna, Atlantic tuna, etc. Also, the season of each type of tuna and the timing of high-volume catch differ, which makes the prices fluctuate greatly.

Therefore, the biggest task of a kaiten-zushi chain buyer is to decide where to import tuna from. Looking for high cost-performance, they watch fluctuations in the market every single day without fail, check the flavor in detail and constantly change the locality.

In other words, the chain restaurant purchaser’s efforts are concentrated on tuna. Restaurants that serve tuna that has lost its fat, is watery or rubbery, clearly either have a purchaser with a poor eye, or poor thawing skills. Therefore, if you are disappointed with that first tuna plate, then reign in your expectations for other toppings. On the other hand, if you enjoy the tuna then you’ll have a lot of other toppings to look forward to.

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Revision date: August 17, 2020

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